Well in that case, I'm marking the gdm Ubuntu task as invalid. The Debian shadow maintainer has agreed that /etc/securetty should mark these X displays as trusted. This hasn't entirely been implemented yet since fusa jumps straight to :20 as its next display number and /etc/securetty only goes up to :3 currently, so this still needs to be implemented (either by supporting wildcards in pam or by listing out all the displays in /etc/securetty), but in either case no code can or should be changed in gdm for this.
Well in that case, I'm marking the gdm Ubuntu task as invalid. The Debian shadow maintainer has agreed that /etc/securetty should mark these X displays as trusted. This hasn't entirely been implemented yet since fusa jumps straight to :20 as its next display number and /etc/securetty only goes up to :3 currently, so this still needs to be implemented (either by supporting wildcards in pam or by listing out all the displays in /etc/securetty), but in either case no code can or should be changed in gdm for this.